What are the three methods for detecting engine knock?

[LeAvery]

There are three methods for detecting engine knock: cylinder pressure detection, combustion noise detection, and engine body vibration detection. The methods for checking engine knock are as follows: Combustion noise detection is a non-contact method with good durability, but its accuracy and sensitivity are relatively low. The cylinder pressure detection method offers higher accuracy, but the sensor's durability is poor, and installation is difficult. The engine body vibration detection method provides high detection accuracy, flexible sensor installation, and good durability, making it the most commonly used knock detection method at present. Here is additional information: To maximize the potential of a gasoline engine, the ignition timing should be controlled close to the critical knock point without causing engine knock. To achieve such performance requirements for the engine's ignition system, knock feedback control must be applied to the ignition timing.